1. Field of the Invention
The present invention relates to an apparatus and method for converting a codec of image data and, more particularly, to an apparatus and method for converting a codec of image data using a decoder of a different video. codec.
2. Description of the Related Art
Video codecs are widely used by movie producers and internet providers. A standard video codec utilized by an image service provider for a wired/wireless network is H.263 and an MPEG (Moving Picture Experts Group)-4.
H.263 is a requisite video codec for terminals. Other standards include H.320 integrated services digital network (ISDN), H.323 internet image terminal standard (IITS), H.324 public switched telephone network (PSTN), or the like. Others, such as European mobile communication providers, provide image services such as video on demand (VOD) using H.263.
MPEG-4 is a video standard based on core techniques of H.263. MPEG-4 compresses and/or restores data to transmit video at a low transfer rate for multimedia communication.
The image data of H.263 has a layer structure made up of a picture layer, a group of blocks (GOB) layer, a macroblock layer, and a block layer.
Referring to FIG. 1, the syntax information of a conventional profile is shown for a picture layer of an image file. The image file has multiple fields. Each of the multiple fields provides directions for moving image data from one location to another location. Referring to FIG. 2, the syntax of the conventional GOB layer illustrating the connections between each of the multiple fields. The GOB layer, like the picture layer, defines locations for moving image data. Both FIGS. 1 and 2 illustrate base line profiles for functionality in the H.263.
Referring to FIG. 3, a visual object sequence and a visual object header are generated of a conventional MPEG-4 bit stream. A visual object layer pages a general video object plane (VOP) mode or a short header mode. When the short header mode is paged from the video object layer, a short header mode syntax is created.
Referring to FIG. 4, a comparison is performed between the short header mode syntax of the MPEG-4 and the syntax of the H.263 baseline profile. The MPEG-4 bit stream is similar to the H.263 bit stream in its performance and structure. Because the header part and/or the syntax of MPEG-4 bit stream are not identical to that of the H.263 bit stream, formatting compatibility issues exist between MPEG-4 and an H.263 decoder. To maintain processing compatibility converting image data between the MPEG-4 and H.263 standards, codecs of each of the standards are required at the mobile terminal. This compatibility problem results in undesirably increasing fabrication costs and volume of a mobile terminal.
Therefore, there is a need for a system that overcomes the above problems and provides advantages over other image data processing systems.